Heat and mass flow forced circulation electric air heater

ABSTRACT

Apparatus for distributing uniformly a mass flow of air to a heater, for distributing heat from the heater uniformly into the air flow thereby uniformly cooling the heater surfaces and for redistributing the mixed and heated air flow over a wide area at the location where the heated air enters a reactor.

United States Patent 1 1 [111 3,784,786

Calvert, Sr. Jan. 8, 1974 [54] HEAT AND MASS FLOW FORCED 2,562,436 7/1951 Pass 219/368 CIRCULATION ELECTRIC AIR HEATER 2,565,769 8/1951 Hatker 219/369 X 2,732,632 1/1956 Koster 219/370 UX [76] Inventor: Willard R. Calvert, Sl., 809 3,261,343 7/1966 Tibell 219/400 UX Teakwood Dr., Severna Park, Md. 21 146 Primary ExaminerBenjamin A. Borchelt 22 Filed; Jam 25, 1971 Assistant Examinerl-l. J. Tudor Attrney-R. S. Sciascia and O. E. Hodges [21] App]. No.: 109,348

' 57 ABSTRACT [52] U.S. Cl. 219/368, 219/374 511 Int. Cl. F24h 3/04 Apparatus for dlstrlbutmg umformly a mass flow of [58] Field of Search to a heater, for distributing heat m the heater 21 47 7 ,77 400 formly into the air flow thereby uniformly cooling the heater surfaces and for redistributing the mixed and 5 I References Cited heated air flow over a wide area at the location where v UNITED STATES PATENTS the heated air enters a reactor, 2;173,102 9/1939 Frank 219 374 ux 5 Claims, 2 Drawing Figures le \8 3| 34 I o as O 1 1 I O '6" 0 0 i w lo 01 O0 1 I 0 0 3| 0' 35 O 0 I 0 O i 0 o -0 0 I I 0 O 26 \0 0 O I 0 0 9 1 O O g 0 22 i O 1 O. i 0 g x 1,

1 HEAT AND MASS FLOW FORCED CIRCULATION ELECTRIC AIR HEATER The invention described herein may be manufactured and used by or for The Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

BACKGROUND OF THE INVENTION Precise distribution of heat and mass flow into reactors is not easily attained but is required. The problem of nonuniform heating has been encountered in the use of CO and H burners in the past. The present invention relates to a means to control the thermal distribution which initiates the oxidation of such components as CO and H The present invention is an attempt to bring a number of variables under control to obtain the required distribution particularly in the catalytic oxidation of air contaminents.

In addition, it is desirable to provide a device to provide a precisely uniform distribution of heat and mass flow in a closely spaced housing. This is especially important when such devices are .used in air purification equipment such as on submarines in the U. S. Navy.

I SUMMARY OF THE INVENTION .The general purpose of this invention is to provide an apparatus for distributing the mass flow of feed air to heater and catalytic chambers of a reactor by directionally controlling the flow of air to minimize nonuniformity from radiant and conducted heat transfer from the heater elements to a position where mass flow enters the reactor.

To attain this desired result the present invention provides a wedge shaped conduit to deliver mass flow to a perforated plate which delivers mass flow uniformity to heater elements and a partially perforated plate having large holes to decrease mass velocity and to cause turbulent mass flow to be deflected over the heater elements followed by another perforated plate to spread mass flow across a uniform plane thereby achieving the uniform temperature across the plane and in the mass flow before entering a catalytic type reactor.

OBJECTS OF THE INVENTION BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an expanded view of the apparatus; and FIG. 2 is a cross-sectional view showing the'apparatus in an assembled condition.

DESCRIPTION OF THE PREFERRED EMBODIMENT '.With continued reference to the drawing, FIG. 1, shows an expanded view of the apparatus.

The apparatus as shown in FIG. 1, comprises a top plate 10, a bottom plate 14, side plates 12 having reinforcing flanges 13 attached thereto, and a back plate 16 secured to said reinforcing flanges 13. As can be seen in FIG. 2, an air inlet such as slot 15 is provided in the bottom plate 14. Positioned in front of back plate 16 is a plate 18 perforated with holes 36. Plate 18 and back plate 16 are positioned such that a wedge shaped chamher is formed to receive airfrom the inlet 15. This wedge shaped chamber with the perforated plate 18 on one side thereof produces uniform mass flow at right angles from its direction of entry. Positioned adjacent perforated plate 18 is a heater assembly. The heater assembly consists of a box type support 20, having rods 22 extending therethrough. Positioned on said rods are circular spacers 24 which separate heating elements 26 from each other across the area within the frame. Said heating elements are connected via wires 28 through terminals (not shown) to an appropriate power source (not shown). Attached adjacent the heater assembly is a second perforated plate 30 with holes 32 along only one edge of the surface thereof. The second perforated plate 30 encloses the heater assembly and is supported by ends 31. It is also noted that a slot may be used instead of holes 32, said slot being shown in the drawings by phantom line 33. The positioning of the holes 32 or of a slot 33 along one edge of said second perforated plate 30, causes the mass flow to be deflected at a right angle, cross the heater elements 26, to efficiently heat the mass flow. Attached adjacent said second perforated plate 30 is a third perforated plate 34, having perforations 37 across the entire surface thereof except directly opposite said holes 32 or slot 33 and being spaced from said second perforated plate by side spacers 35. Said third perforated plate functions to uniformly distribute the mass flow, which has been uniformly heated before it enters the catalytic heater as shown in FIG. 2, at 40, through one side of the heater shown as screen 38, in FIG. 1.

In operation the apparatus parts forming the wedge shaped chamber deliver mass flow to the first perforated plate 18, which has holes 36 sized and located to deliver the mass flow uniformly to the heater elements 26, for example, at a mass velocity as high as 4.5 lbs (air) per square inch hole area per minute. Any of several configurations would be operable The combination of the perforations 32, or slot 33 on one side of the second perforated plate 30, with the circular spacers 24, allows a cross flow across the heater elements 26. Said turbulent mass flow over the heater elements surfaces results in an averaging of the heater element heat surface temperatures. In addition, the mass flow from I the second perforated plate 30 is baffled by the third perforated plate 34, which serves to minimize the effect of radiant energy flow and conducted heat from the heater assembly in close spacing of heaters within the housing which contains both the heater assembly and f the catalytic reactor.

It will be apparent from the foregoing that the invention provides apparatus of novel and advantageous construction for distributing the mass flow of feed air to heater and catalytic reactor by directionally controlling the flow of air to minimize non-uniformity from radiant and conducted heat transfer from heater elements to a position where mass flow enters the reactor. The improved apparatus is simple and rugged in construction and provides the very distinct advantage of uniform heater life.

It is understood that the invention is not limited to exact details of the construction shown and described, for obvious modifications will occur to persons skilled in the art. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A heat and mass flow distribution device comprising:

an inlet for mass flow;

a first deflecting and distributing means connected at a right angle to said inlet to deflect mass flow from said inlet and distribute said flow uniformly in cross section;

a heating means connected to said first deflecting and distributing means to heat said mass flow; a second deflecting means connected to said heating means to redirect said mass flow laterally through said heating means to cause accumulative mixing of the heated mass flow; baffling means connected to said second deflecting means to minimize the effect of radiant energy flow and conducted heat from said heating means; and

outlet connected to said baffling means to supply said mass flow which has been uniformly heated and distributed to a desired location.

2. A heat and mass flow distribution device as defined in claim 1 wherein said first deflecting and distributing means comprises a wedgeshaped chamber connected to said inlet at the broad base of the wedge and having a perforated plate for one of the inclined sides of the wedge to pass air from said chamber.

3. A heat and mass flow distribution device as defined in claim 1 wherein: a

said heating means includes a grid of heating elements positioned across the mass flow and said second deflecting means comprises a plate having perforations through said plate located near one edge thereof and connected to said heating means to deflect said mass flow laterally around the elements in said grid. 4. A heat and mass flow distribution device as in claim 3 wherein:

said heating means further includes spacers to separate said heating elements and to allow mass flow laterally around the elements in said grid. 5. A heat and mass flow distribution device as defined in claim 1 wherein:

said heating means includes a grid of heating elements positioned across the mass flow and second deflecting means combines a plate having a slot through said plate located near one edge thereof and connected to said heating means to deflect said mass flow laterally around the elements of said grid. 

1. A heat and mass flow distribution device comprising: an inlet for mass flow; a first deflecting and distributing means connected at a right angle to said inlet to deflect mass flow from said inlet and distribute said flow uniformly in cross section; a heating means connected to said first deflecting and distributing means to heat said mass flow; a second deflecting means connected to said heating means to redirect said mass flow laterally through said heating means to cause accumulative mixing of the heated mass flow; baffling means connected to said second deflecting means to minimize the effect of radiant energy flow and conducted heat from said heating means; and outlet connected to said baffling means to supply said mass flow which has been uniformly heated and distributed to a desired location.
 2. A heat and mass flow distribution device as defined in claim 1 wherein said first deflecting and distributing means comprises a wedge shaped chamber connected to said inlet at the broad base of the wedge and having a perforated plate for one of the inclined sides of the wedge to pass air from said chamber.
 3. A heat and mass flow distribution device as defined in claim 1 wherein: said heating means includes a grid of heating elements positioned across the mass flow and said second deflecting means comprises a plate having perforations through said plate located near one edge thereof and connected to said heating means to deflect said mass flow laterally around the elements in said grid.
 4. A heat and mass flow distribution device as in claim 3 wherein: said heating means further includes spacers to separate said heating elements and to allow mass flow laterally around the elements in said grid.
 5. A heat and mass flow distribution device as defined in claim 1 wherein: said heating means includes a grid of heating elements positioned across the mass flow and second deflecting means combines a plate having a slot through said plate located near one edge thereof and connected to said heating means to deflect said mass flow laterally around the elements of said grid. 